@JEG2 Hi. First of all, thank you for the book. I learned a lot.
I have a question about data validation. In the book you are doing it in the boundary layer. What if my validator has a bug and and invalid data gets through to the core? Is it OK if my core raises an error then? Or better to build the core that never breaks?
Example: A question can only accept answers “yes” and “no”. Every time you answer a question, it gets added to the list of responses in the quiz. But if the user somehow manages to answer “maybe”, which is invalid and the validator doesn’t catch it, we have options to: don’t add response to the list and return quiz unchanged, crash, return an error tuple.
Error tuple is not good for composition, not doing anything and returning the quiz is probably not what the user expected, and raising sounds quite good to me.
I hope I described the problem. What are your thoughts?
